The benefit of exercising on a direct drive exercise bicycle is well known. Direct drive exercise bicycles typically utilize a high-inertia flywheel driven by a fixed-gear drive train. The flywheel is driven by the rider up to relatively high revolutions per minute (rpm). Because of the direct drive feature, the drive train must rotate at a fixed ratio of rpm as compared to the flywheel based on the gear ratio. One benefit of the direct drive exercise bicycle is that the direct drive gear train provides "pedal-through assistance" for the rider. The "pedal-through" feature assists the rider by pushing the pedal through the top and bottom dead center pedal positions to help make the transition smooth and efficient. Other benefits are derived from the direct drive interaction between the inertia flywheel and the crank arms to which the rider's feet are attached. The inertia flywheel provides a smooth, non-jerky pedaling rhythm which provides an efficient and rigorous exercise for the rider, especially at relatively high rpms, such as 60 to 100 rpm.
In the application of this invention to an inertia flywheel exercise bicycle, positive drive is required to rotate the inertia wheel in order to overcome regulated retardation torque applied by brake means used to provide resistance against which the rider/operator works. The inertia wheel provides means for continued drive train (wheel to crank to leg) movements during those periods when the crank is in top dead center or bottom dead center positions, where the rider's legs are somewhat weaker in providing rotary motion to the activating crank arms. The flywheel affords smooth and steady operation for the rider.
The direct drive relationship between the flywheel and the drive train is also a drawback of exercising on this type of bicycle. The direct drive relationship is inconvenient when the rider wishes to quickly stop the pedals, or loses the pedaling rhythm required to keep up with the rotating flywheel. In the usual flywheel exerciser employing such a direct drive relationship, it is necessary for the rider/operator to gradually decrease his cranking rate in order to slow down the inertia wheel. The rider cannot suddenly stop pedaling inasmuch as the inertia flywheel continues to drive the crank arms.
Of similar importance is the desirability of providing pedal assist to the rider/operator's legs when cranking at a speed slower than that necessary to positively drive the flywheel, and providing for a gradual reengagement and lockup between the pedal actuated drive shaft and the free wheeling flywheel in order to avoid abrupt impact when reengaging the moving flywheel.
It is with these issues in mind that the present invention was developed.